Linkage studies in Menkes' disease The Xg blood group system and C‐banding of the X chromosome

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Abstract
Menkes' disease is a rare, genetically determined disturbance of copper metabolism which is transmitted as an X-linked recessive character. By comparative gene mapping it can be suggested that the most likely localization of the gene for Menkes' disease is on the long arm of the human X chromosome close to band q 13. This regional assignment is supported by the present analysis of the genetic relationship between the Menkes locus, the Xg locus, and the centromere in five Danish families. The evidence suggests close linkage between the Menkes locus and the centromere. The most likely value of the recombination fraction is 0.05 and the maximum lod score is above the conventional +3 limit. Linkage analysis of the Menkes locus and the Xg locus showed a recombination value of 0.24, but the maximum conditional score is 0.28, which is far below the conventional +3 limit. The present study demonstrates a successful application of a chromosomal morphological marker in linkage analysis and carrier detection of a single gene disorder. The close linkage between the gene for Menkes' disease and the centromere region was used to improve the classification of several females in whom the copper uptake into cultured fibroblasts was either inconclusive or not available.